but most of the time it would really be on sponsorship.Is it ethical? sort of and since its part of marketing then its just normal.
In my country and neighbor countries (Eastern Europe) this is ethical.
"Everyone makes money as they can" . So you can't complain and tell someone that he is "unethical". People will not understand it. And one addition: In Eastern Europe, to be sponsored by gambling site is one of the least "unethical" things to complain for. Here a lot of people doing much more terrifying things and people around don't consider it as "unethical"